The present invention relates generally to the field of modular communication plugs and, more particularly, to the generation of complementary crosstalk in a communication plug such that performance with connector jacks is optimized.
Telecommunications and data transmission systems have evolved in recent years to accommodate the increasing demand for high speed, multi-media services. Accordingly, higher and higher frequencies are being transmitted across network infrastructure originally designed for lower throughput. Although present day cables and wiring, can, theoretically, handle such increased frequencies and traffic volume, the wiring paths themselves become, in effect, antennae that both radiate and receive electromagnetic radiation, thereby creating crosstalk problems. Crosstalk is particularly problematic in systems incorporating multiple wire pairs. Unfortunately, the plugs and jacks that are most commonly used in interconnecting cables and hardware, such as distribution modules, generally include up to eight wires (four wire pairs) that are necessarily oriented both parallel and close together, a condition that leads to excessive crosstalk, even over short distances, and which is exacerbated as the frequency of the signals or the data rate is increased.
Various techniques have been used for reducing crosstalk in communication plugs and cables, such as shielding individual pairs, helically winding twisted pairs, or, where possible, increasing the physical separation of one pair from another. The crosstalk problem, however, cannot be managed through a simple minimization or reduction approach. While it may be desirable in future applications to eliminate virtually all crosstalk in a communication plug, legacy systems (i.e., current jacks) require a predetermined amount of crosstalk in the plug for optimum performance. Legacy jacks are engineered to compensate for crosstalk in the communication plug; thus, a well designed plug should generate crosstalk that is complementary to that used in the jack so the combination of the two crosstalk signals cancel each other out.
For the crosstalk signals generated in the plug and the jack or connector to be completely complementary, they should be of equal magnitude and be 180.degree. out of phase with one another. The crosstalk signals generated in the plug and the jack are separated initially by some defined distance, which results in a propagation time delay before the signals combine. This propagation delay can cause the phase difference between the two crosstalk signals to shift from the desired 180.degree. to some other value, which prevents the plug and jack crosstalk signals from completely canceling one another out. It is therefore desirable, that the complementary crosstalk in the plug be generated proximal to the jack to minimize the propagation delay for the complementary crosstalk signals.
Thus, what is sought is a communication plug having engineerable parameters that can be modified to generate a desired level of crosstalk to adapt to the compensating crosstalk characteristics of a jack or connector in which the plug will be used. Preferably, the communication plug generates the crosstalk near the plug-jack interface to minimize the propagation delay between the crosstalk signals from the respective components.